Spyware is a type of malware that is installed on computers and collects information about users without their knowledge. The presence of spyware is typically hidden from the user. Typically, spyware is secretly installed on the user's personal computer. Sometimes, however, spywares such as keyloggers are installed by the owner of a shared, corporate, or public computer on purpose in order to secretly monitor other users. More: http://en.wikipedia.org/wiki/Spyware

Adware or advertising-supported software is any software package which automatically plays, displays, or downloads advertisements to a computer after the software is installed on it or while the application is being used. Some types of adware are also spyware and can be classified as privacy-invasive software. More: http://en.wikipedia.org/wiki/Adware

Malware, short for malicious software, is software designed to infiltrate or damage a computer system without the owner's informed consent. The expression is a general term used by computer professionals to mean a variety of forms of hostile, intrusive, or annoying software or program code.[1] The term "computer virus" is sometimes used as a catch-all phrase to include all types of malware, including true viruses. More: http://en.wikipedia.org/wiki/Malware

A rootkit is a software program or coordinated set of programs system whose purpose is to gain control over a computer system. In effectively all cases, this is a hostile act, though not necessarily hostile to any specific computer system, organization, or person. The attack may be purely adventitious, made against computers reached, for instance through the Internet, which have a vulnerability (a "hole" or "backdoor") to the attack technique being used... more:http://en.wikipedia.org/wiki/Rootkit

Spywares are the program which are used to monitor/Log the activity performed on a computer. These are used to spy on some one either for legal or illegal perpose. Example: Keylogger applications.Adwares are the programs which delivers ads to your computer. They consume your network.Malwares are the program with malicious intention. It can be damaging your computer, spying on you or any other malicious task.

I have read your stuff. It is really interesting description about spyware, malware and adware. I am glad to share your valuable knowledge. After reading your stuff I can know the difference among them very well.

Well, I'm using a software wherein it usually check the performance of your pc and will show you the reason why your pc gets slow. Usually malware i detected. The software is called "pc health advisor" and I'm using it since last year and never fail me even once/